How is it ok for Avraham Avinu to serve Chemah-curds, chalab-milk and habaqar- kid/lamb/yearling to the divine guest ? The angels ate these food. Its said Avraham obeyed Torah even before Sinai ? So is it ok to eat meat and milk at the same time ?

Dear Basil: According to the rabbinic tradition that Avraham obeyed all the rules of the Torah, the answer to your question is that Avraham served the dairy dish first and the meat dish second. This is consistent with the laws of Kashrut. In fact, this is also the order in which the various items appear in the verse that describes Avraham's actions. But the laws of Kashrut do not permit eating meat and milk together.